Type arrangement in endless band line printers



Sept. 3, 1

8 J. c. SIMS, JR

TYPE ARRANGEMENT IN ENDLESS BAND LINE PRINTERS Filed Sept. 19, 1966APPLIED DATA COMPARATOR oooooooooooooooooooooo (3 E E y.

*1 3 o E o OOOOOOOOOOOOOOO INVENTOR JOHN C. SIMS, JR.

TORNEY United States Patent 3,399,619 TYPE ARRANGEMENT IN ENDLESS BANDLINE PRINTERS John C. Sims, .lr., Sudbury, Mass, assignor to Mohawk DataSciences Corporation, East Herkimer, N.Y., a corporation of New YorkFiled Sept. 19, 1966, Ser. No. 580,411 15 Claims. (Cl. 10193) ABSTRACTOF THE DISCLOSURE A type carrier for an on-the-fly printer includes aplurality of non-connected, abutting type slugs moving at a constantvelocity about a closed path defined by a pair of parallel rails and tworotatable pulleys having peripheral surfaces tangent to the ends of therails. Each type slug is provided with a longitudinal groove on a sideof the slug opposite the side which contacts the path and a resilientband encircles the path through the slug grooves to hold the slugs inplace. The pulleys are provided with teeth and one of the pulleys isdriven to propel the slugs, which have mating teeth, along the path.

This invention relates to printing and, in particular, to line-by-lineprinters of the type employing a sequence of type characters which arecontinuously moved past a line that is to be printed, where printing isaccomplished by actuation of transducers, such as hammers, when the typecharacters are appropriately positioned.

Line printers of this type often employ a closed chain of type which ismoved around a loop and past the line to be printed. Consequently,changing character types is relatively complicated, requiring that thechain be removed and dismantled. This disadvantage is partially overcomeby using a train of loose type elements which travel betweenconstraining tracks or within a slot. In this case, however, themechanism containing the type elements is relatively complex. In thepresent invention, loose type elements are maintained against a typerace by tension with a loop of spring. In this simple manner, the typeelements are constrained to movement along the path defined by the typerace and replacement or reordering of type elements can be accomplishedby merely stretching the spring.

In the preferred embodiment of the invention, several type charactersare supported on each type element to reduce the number of type elementsrequired and to enable the use of more manageable (larger) type elementswhile retaining closely-spaced type characters.

A further advantage is gained by the unique location of the typecharacters on the type elements. In printers of this general form, thetype characters are located on the outer surface of the loop; that is,the surfaces of the type characters are perpendicular to the plane ofthe loop. Since it is generally desirable to pass the document to beprinted in the upward and backward direction past the printing mechanismto permit the document to be read immediately after printing, the trainof type lies in a plane that is perpendicular to the plane of thedocument, with the result that the printer is inherently bulky. Thisdisadvantage is overcome in the present invention by placing the typecharacters on an edge of the type elements; that is, the surface of thetype characters is essentially parallel to the plane of the loop. As aresult, the plane of the loop is essentially parallel to the plane ofthe document, reducing the physical size of the printer.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention, as illustratedin the accompanying drawings.

3,399,619 Patented Sept. 3, 1968 In the drawings:

FIGURE 1 is a functional design of the inventive printer showing, inparticular, the preferred configuration of the type elements.

FIGURE 2 is a detailed drawing showing a type element.

As shown in FIG. 1, a document 2 is incrementally moved upward, one lineat a time to be printed. Printing is accomplished by forcing thedocument against type characters by the use of printing transducers 4,such as hammers, under the control of a hammer drive assembly 6. Aninked ribbon is located between the document and the type elements, butis not shown for simplicity. The type characters are raised on the rearsurfaces of type elements 8 and are continuously moved past the line ofprinting transducers.

As shown in greater detail in FIG. 2, several raised type characters 10are supported on each type element 8. The type elements contain two fiatsurfaces 12 separated by a groove 14. The type characters are supportedon a surface 16 which is parallel to the length of the groove 14 andwhich extends in essentially the same direction as the depth of thegroove. Actually, the type-character sup-porting surface 16 is slantedslightly (as shown in FIG. 2) to permit the document 2 (FIG. 1) toapproach the printing region from below and slightly behind the printingmechanism for convenience of construction. Each type element alsocontains a drive surface 18 (FIG. 2) containing teeth 20.

The type elements 8 are maintained in a type race with the configurationof a closed loop or path, as shown in FIG. 1. The type race consists ofan idler pulley 22, a drive pulley 24, and two straight sections oftrack 26, 28. The pulleys and tracks are shaped to loosely conform tothe shape of the type elements; that is, the pulleys and tracks aregrooved to conform with the under section of the type elements and theouter rear surface of the pulleys and tracks are slanted to conform withthe slope of the type-element supporting surface 16.

The type elements 8 are maintained in the type race by a loop of curledspring 30 of the type generally used to drive the take-up reels inmotion picture projectors. The spring 30 engages the grooved portions ofthe type elements as shown in FIG. 2. Thus, by merely stretching thespring slightly, type elements can be replaced or rearranged in the typerace.

The type elements are driven around the type race at a substantiallyconstant speed by a drive gear 31 mounted on drive pulley 24-. A motor34 provides continuous rotation to the drive gear which, in turn, coactswith the teeth 20 (FIG. 2) on the type elements. The direction ofrotation of the drive pulley 24 (counterclockwise in FIG 1) is selectedto push the type elements along the printing line to avoid slack betweenthe type elements.

The printing transducers 4 are selectively actuated at appropriate timesas the type characters pass the document line. While a separatetransducer is shown for each character position along the line to beprinted, a lesser number of transducers can obviously be used inconjunction with various techniques that are known in the art, such aslateral paper shifting or double-width transducers with spaced charactertypes. The actuation of the transducers is controlled by the hammerdriver assembly 6 which, in turn, is controlled by the output of acomparator 36 and a timing unit 38, according to well-known techniquesthat are used in conventional chain or train printers. The timingcircuit 38 receives data which depends upon the position of thecharacter types in the type race as the printing mechanism is inoperation. This timing data can be received in coded form in parallel bymagnetic, optic or other techniques, or can be developed by the timingcircuit from a sequence of timing pulses. The

latter technique is preferred as it reduces the complexity of therequired sensing mechanism. As shown in FIG. 1, a timing gear 32 ismounted at the center of track 26 and is driven by the teeth on the typeelements. The timing gear contains radial, magnetically-sensiblemarkings 40, which are spaced apart to coincide with the spacing betweencharacter types on the character elements 8. (Obviously, a lesser numberof markings 40 can be used in conjunction with an oscillator or othertiming pulse generator to provide intermediate timing data.) Themarkings 40 are magnetically secured by a transducer 42 to supplysignals to the timing circuit 38. Since the timing gear is centeredalong the printing line, irregularities in the dimensions of the typeelements cause a minimum of timing error. Overall synchronization isaccomplished by another magnetic transducer 44 which senses a singlemarking which is placed on only one of the type elements 8 for eachcomplete type font. In the preferable case, where several fonts of typeare present around the type race, this synchronizing markin-g is presenton a corresponding type element in each font (e.g. the first typeelement in each font).

The comparator 36 receives applied data indicative of the characters tobe printed and timing data indicative of the positions of the charactertypes. As a result of comparisons, signals are supplied to the hammerdriver assembly 6 to actuate the appropriate hammers. Signals from thetiming circuit 38 are also applied to the hammer driver assembly tocontrol the selection of the appropriate hammers for actuation.

In the preferred embodiment of the invention, the character types 10(FIG. 2) are spaced slightly farther apart than are the characterpositions (columns) on the document. This produces the well-knownDoppler effect, wherein the character types are aligned with thecharacter positions on the document in sequence, rather than all at onetime. In this manner, sequential comparison with a single comparator ispossible, reducing the complexity and expense of the hammer controlsystem. Obviously, the character types can alternatively be spacedslightly closer together than the character positions to permit similaradvantages.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formand details may be made therein without departing from the spirit andscope of the invention.

What is claimed is:

l. A printer for presenting characters along a printing line on asurface of a document, comprising in combination:

a sequence of type elements mounted for travel around a closed trackhaving a straight section adjacent to the printing line on the documentand having a return section, both said sections lying in a common planethat is substantially parallel to the surface of the document, each typeelement containing at least one raised type character on an edge of theelement that is essentially parallel to the plane of the track, the typeelements and type characters being movable along the straight section ofthe track adjacent to the printing line and then back along the returnsection of the track;

means for providing substantially constant movement of the type elementsaround the track;

at least one transducer arranged to force a document against a typecharacter to effect printing when the transducer is actuated; and

transducer control means responsive to applied data and to the positionof the type elements in the track to actuate the transducer to print apredetermined character.

2. The device described in claim 1, wherein a plurality of transducersare employed, one for each of a plurality of character positions along aprinting line.

3. The device described in claim 2, wherein a separate transducercorresponds to each character position along a printing line.

4. The device described in claim 1, wherein the type elements arearranged in a track without being physically connected to theirneighboring type elements.

5. The device described in claim 4, wherein the track rigidly definesthe closed path of travel and wherein the type elements are maintainedagainst the track by a flexible member.

6. The device described in claim 1, wherein each type element contains aplurality of type characters.

7. The device described in claim 1, wherein the position of the typeelements in the path is determined by magnetic sensing means.

8. A type carrier for an on-the-fiy printer, comprising, in combination:

support means defining a closed path;

a plurality of type members adapted to move along said path, each saidmember supporting at least one type character and having a groovedrecess on a side opposite a side of said member which contacts saidsupport means;

a band encircling said path in the grooves of said type members wherebysaid members are maintained in contact with said support means; and

means for propelling said members along said path.

9. The type carrier set forth in claim 8 wherein said support meanscomprises:

a pair of parallel rails; and

a pair of rotatable pulleys mounted between the ends of said rails, saidpulleys having peripheral surfaces substantially tangent to outersurfaces of said rails.

10. The type carrier set forth in claim 9 wherein said propelling meanscomprises:

motor means for rotating at least one of said pulleys.

11. The type carrier set forth in claim 9 wherein:

said rails and pulleys are provided with a continuous central groove andwherein said type members are shaped substantially in the form of a W,the central point thereof being adapted to reside in said central grooveand to define said band receiving grooved recess and one of the outerlegs thereof being adapted to support said type character.

12. The type carrier set forth in claim 10 wherein said type members areprovided with teeth and said pulleys are provided with mating driveteeth, whereby said type members are positively propelled along saidpath.

13. The type carrier set forth in claim 8 wherein said type members arein abutting relationship with one another whereby each is propelledalong said path by the pushing force exerted by the adjacent member.

14. The type carrier set forth in claim 8 wherein said band is made ofelastic material.

15. The combination set forth in claim 8, further comprising:

a hammer mounted adjacent said type carrier and spaced apart therefromby an amount suflicient to admit a record medium; and

actuating means operating in timed relation with the movement of saidtype members to drive said hammer against said record medium to forcethe latter against a selected one of said type characters whereby animpression of said character is formed on said record medium.

References Cited UNITED STATES PATENTS 1,617,876 2/1927 Swanson 101-377X 2,902,930 9/ 1959 Hurlbut 101-381 2,936,704 5/ 1960 Hense 101-933,049,990 8/ 1962 Brown et al 101-93 3,117,514 1/1964 Doersam 101-933,224,366 12/1965 Cunningham 101-111 X WILLIAM B. PENN, PrimaryExaminer.

